UnistageTM Design

Simplicity of design, especially in the direct signal path, has always been the hallmark of Balanced Audio Technology’s purist approach to circuit topology.  Some advocates of this purist approach like to talk about a "direct wire with gain" as being the ideal circuit.  The VK-33 preamplifier deftly meets this simple design criterion.  Effectively, the signal in the VK-33 preamplifier is transmitted through only one gain stage.  It is a design that is free from the negative artifacts attributable to both extremes of modern preamplifier designs: passive preamplifiers at one end of the spectrum and multistage buffered active circuits at the other.

The benefit of the UnistageTM circuit is that it provides the ultimate simplicity of amplifying the incoming signal only once, while using no global feedback to double-back on the straight-through integrity of that signal.  Imagine telling a joke to your friends and telling them to “pass it on”….   Pass it on enough times and you won’t recognize the joke.  Pass the music through too many gain stages, and you’ll no longer recognize the genius and beauty of your favorite recordings.

Vacuum Tube Current Sources & 6922 Gain Stage

The Balanced Audio Technology VK-33 preamplifier is the fifth generation preamplifier from BAT to use the 6922 tube for its UnistageTM circuit design.  The low restriction signal path of the VK-33 preamplifier is substantially improved through the use of “SE” transformers in the power supply.  Vacuum tube current sources further improve the linearity of the gain stage to yield a more open and textured sound than a simple resistor-based solution.  In addition, with the purchase of BAT’s X-PAK accessory, more than one type of vacuum tube can be used as the current source for the VK-33 preamplifier.

This X-PAK accessory allows the customer to fine tune the VK-33 preamplifier’s sound to best meet their individual needs.  The 6922 tube, used in the gain stage, is also one of the most widely produced vacuum tubes in history, thus allowing substantial fine tuning of the sound from the active devices in the signal path as well.  Of course, as you’d expect from Balanced Audio Technology, the VK-33 preamplifier can be fully upgraded to the VK-33SE preamplifier at a later date.

Fully balanced design

Of course, the VK-33 preamplifier is balanced.  Balanced Audio Technology staked its reputation on this principal of circuit design from day one.  Today, it isn’t hard to find many followers in the industry.  Why do we believe that balanced is better?  In our opinion, balanced topology simply provides a complete signal representation.  Something magical happens when you free yourself from the limitations of the single-ended structure with its half-signal processing.  If a one-handed craftsman can be very good, imagine what he could do with two hands.

It is fairly common to associate the benefits of balanced design with improved signal integrity when dealing with long interconnects, for example.  In fact, the true benefits of a balanced approach to circuit design go much further than signal transmission.  These benefits include such fundamental aspects of design as the interaction between the power supply and its associated gain stage.  It is now common wisdom that the power supply should be considered a part of the signal path.  However, whereas the sonic contribution of the power supply can be overwhelming in a single-ended design, it is much less of a concern in a balanced circuit.  As the circuit becomes more symmetrical, the residual effect of the power supply becomes less intrusive.  In effect, the demand on the power supply is reduced, making it easier to design a balanced circuit that conforms more closely to the engineering ideal.

For added convenience, the VK-33 incorporates a mix of balanced and single-ended inputs as well as outputs.

Shunt volume control

The VK-33 preamplifier employs a proprietary electronic shunt volume attenuator that offers one hundred and forty steps of 0.5dB resolution.  Only a single Vishay bulk foil resistor per phase – the most precise and thermally stable resistor available – is in the signal path.  Discrete metal film resistors are used to bleed the unused signal to ground.  With this circuit, only the highest quality Vishay resistor is in series with the signal.  In addition, the one hundred and forty steps give precise repeatable volume settings that sound continuous to the human ear.  With the VK-33 preamplifier, you can always get the volume just right!

Optional Phono Module

The user can order the VK-33 preamplifier with Balanced Audio Technology’s outstanding VK-P3 phono card.  The VK-P3 phono card is a solid-state phono module that is designed to compete with external phono stages that are twice its price.  It offers switch-selectable moving magnet or moving coil gain settings, and provides a convenient, high performance, single-box solution for the vinyl record aficionado.

Superb User Interface

The VK-33 preamplifier is easy to use right out of the box.  It is also just as easy to customize.  Its user interface has been widely acknowledged to be one of the best and perhaps the most flexible in the industry.  You can dim the display (or turn it off entirely) from the comfort of your chair by using the BAT remote.  Fade the music gently at the touch of one button.  Name your sources.  For example, name your home theater playback input THTR.  Fix the volume for your THTR input to allow easy master control of your home theater system from your pre/pro remote.  Switch phase from your chair to see if a recording was made in reverse absolute polarity.  The list of features is extensive.  If you only use one of the many delightful features of the VK-33 preamplifier, you’ll appreciate the thoughtfulness behind its design.

Summary

Balanced Audio Technology continues to strive for excellence in every aspect of its business: from our emphasis on exceptional customer support, to innovation in product design, and, most importantly, to the musical enjoyment provided by every component we manufacture.  With the VK-33 preamplifier, BAT provides demonstrable proof of our commitment to excellence; from the elegant aesthetic improvements in the industrial design of this new model to the use of Special Edition transformers, which provide a lower restriction power supply.  These engineering changes and their corresponding sonic benefits are part of our ongoing drive to provide the best possible sound for our customers.

All you need to do is listen…………